A method of the type mentioned at the beginning is known from DE 197 39 456. In accordance with it, a modification is produced in a core of an optical waveguide with a single pulse or a sequence of pulses having a defined number of pulses. The optical waveguide core is surrounded by an optical waveguide cladding, the material of which has a lower refractive index than that of the optical waveguide core. The pulse intensity is chosen so that the destruction threshold is exceeded with each single pulse. By a micro-explosion in the material, scattering centres are produced, which effect a scattering of a part of the radiation guided in the optical waveguide core in all directions. From the article Physical Review Letters, Vol. 74 (1995), pages 2248 to 2251 is known the use of laser pulses having a duration of a few 10 ns down into the sub-picosecond range for material changes in the micrometer range by virtue of the low energy.
The production of grating structures in an optical waveguide is known from U.S. Pat. No. 6,384,988. The optical waveguide consists of a photosensitive material, which is illuminated according to the grating structure.
The last-named method has the disadvantage that it can only be used with photosensitive optical waveguide materials. The other mentioned methods from the prior art do not enable any controlled coupling of light out of the optical waveguide or coupling of light into the optical waveguide. The method of DE 107 39 456 only allows the scattering of light from the optical waveguide in all directions.